近日，美国康奈尔大学B. J. Ramshaw团队报道了α-RuCl₃声子霍尔粘度与本征热霍尔效应。该研究于2026年4月22日发表在《自然》杂志上。

热霍尔效应已在多种磁性绝缘体中被观测到，但其起源仍存争议。尽管一些研究将其归因于本征机制，例如具有贝里曲率的热载流子，另一些研究则提出非本征机制，例如热载流子受晶体缺陷的散射。甚至连热载流子的本质也尚不明确：磁子、声子以及分数化自旋激发都曾被提出。解决这些问题对于量子自旋液体的研究至关重要，尤其是对于α-RuCl₃，其中观测到的量子化热霍尔效应被认为源于马约拉纳边缘模式。

研究组利用声法拉第效应的超声测量，证明了α-RuCl₃中的声子具有霍尔粘度——这是一种非耗散的粘度，可以旋转声子偏振并偏转声子热流。他们证明，声子霍尔粘度会产生一个本征的热霍尔效应，该效应在数值上可以解释α-RuCl₃中测得的相当大一部分热霍尔信号：α-RuCl₃中的热霍尔效应来源于声子，并且是本征的。更广泛地说，研究组证明了声法拉第效应是探测声子霍尔粘度及相关声子贝里曲率的有力工具，为发现和研究那些无法通过常规实验揭示的物质奇异态提供了新途径。

附：英文原文

Title: Phonon Hall viscosity and the intrinsic thermal Hall effect of α-RuCl3

Author: Shragai, Avi, Horsley, Ezekiel, Kim, Subin, Kim, Young-June, Ramshaw, B. J.

Issue&Volume: 2026-04-22

Abstract: The thermal Hall effect has been observed in a wide variety of magnetic insulators1,2,3,4,5,6,7,8,9, yet its origins remain controversial. Although some studies attribute the effect to intrinsic mechanisms10,11,12,13,14, such as heat carriers with Berry curvature, others propose extrinsic mechanisms15,16,17, such as heat carriers scattering off crystal defects. Even the nature of the heat carriers is unknown: magnons, phonons and fractionalized spin excitations have all been proposed. Resolving these issues is essential for the study of quantum spin liquids, and particularly for α-RuCl3, in which a quantized thermal Hall effect has been attributed to Majorana edge modes18,19. Here we use ultrasonic measurements of the acoustic Faraday effect to demonstrate that the phonons in α-RuCl3 have Hall viscosity—a non-dissipative viscosity that rotates phonon polarizations and deflects phonon heat currents. We show that phonon Hall viscosity produces an intrinsic thermal Hall effect that quantitatively accounts for a substantial fraction of the measured thermal Hall effect in α-RuCl3: the thermal Hall effect in α-RuCl3 is due to phonons, and it is intrinsic. More broadly, we demonstrate that the acoustic Faraday effect is a powerful tool for detecting phonon Hall viscosity and the associated phonon Berry curvature, offering a new way to uncover and study exotic states of matter that elude conventional experiments.

DOI: 10.1038/s41586-026-10420-y

Source: https://www.nature.com/articles/s41586-026-10420-y